Very interesting paper providing empirical evidence along with substantial data to demonstrate pros and cons of both monogamy and polygyny.
The introduction itself demonstrates key factors for both points of views, therefore it is up to the reader to concur with the given data and realize that equilibrium of both are determined on wider structures of social thinking.
Source-
http://hubcap.clemson.edu/~sauerr/seminar_papers/gould_monogamy.pdfThe Mystery of Monogamy
Eric D. Gould, Omer Moav, and Avi Simhon
The Hebrew University
August 20, 2003
Abstract
This paper examines why developed countries are monogamous while rich men
throughout history have tended to practice polygyny (multiple wives). Wealth inequality
naturally produces multiple wives for rich men in a standard model of the
marriage market. This paper argues that the sources of inequality, not just the level
of inequality, determine the equilibrium degree of monogamy or polygyny. In particular,
when inequality is determined more by disparities in human capital versus
non-labor income (such as land, capital, corruption), the outcome is more monogamous.
This explains why developed countries, where human capital is the main
source of income and inequality, are monogamous while less-developed economies
tend to be polygynous. The results are driven by the larger inequality in the value
of women in the marriage market in modern economies. When the value of human
capital increases, rich men increasingly value quality women who can help them raise
quality children more efficiently. As a result, high quality women are valued much
more than low quality women, which makes polygyny less affordable for rich men.
In this manner, we show that male inequality generates polygyny, but female inequality
reduces it. Using data from Cote d’Ivoire, we provide evidence for all the
main implications of the model. In particular, we control for a man’s total income
and show that polygyny increases with non-labor income but decreases with labor
income and education. These patterns are strong even within social groups where
norms regarding polygyny are likely to be constant.
Introduction
Throughout history, wealthy men have tended to mate with multiple wives. This practice,
known as polygyny, exists in 850 of the 1170 societies recorded in Murdock’s Ethnographic
Atlas (Hartung (1982)). Polygyny is still prevalent in much of Africa where the percent of
women living in polygynous households ranges from 25% to 55% in the Western, Central,
and Eastern parts (Lesthaege (1986)). Moreover, polygyny is very easy to explain theoretically
— male inequality in wealth tends to generate inequality in the number of their
wives (Becker (1991)). If all men were equal, there would be no reason for a woman to
become the second wife of a man when she can just as easily be the only wife of someone
just as good. However, it is not well understood why polygyny is virtually non-existent
in modern industrialized societies, or in other words, why polygyny is so strongly associated
with primitive economies both today and throughout history. Given the large and
often staggering disparities in wealth in many highly developed countries, it is somewhat
of a mystery that monogamy has emerged almost universally in the marriage market of
advanced economies.
Therefore, the primary goal of this paper is to offer an explanation for the emergence
of monogamy as an equilibrium outcome even in the presence of persistently high levels
of income inequality. Our model demonstrates that a key factor explaining the practice
of monogamy versus polygyny is not just the level of inequality, but also the composition
of inequality. In particular, income is derived from labor income, which is a function
of human capital, and non-labor income such as land, physical capital, corruption, etc.
The model shows that the marriage market equilibrium becomes more monogamous as the
level of inequality is determined more by disparities in human capital versus disparities
in non-labor income. This result is consistent with the idea that inequality in advanced
economies is determined more by differences in human capital, while inequality in lessdeveloped
societies is primarily due to a skewed distribution of non-labor income.1
A key assumption of the model is that high quality men and women are more efficient
in producing higher quality children, which generates a comparative advantage for high
quality parents in raising higher quality children. Therefore, the rich men in less-developed
1For example, labor income explains 72% of the variation in total income for male heads of households
in the United States 1990 Census versus only 54% in Cote d’Ivoire in 1986 (see the empirical section for
a description of the Cote d’Ivoire data). Using log income and log wages, these numbers are 18% for the
US and 6% for Cote d’Ivoire. Also, this notion is consistent with the empirical growth literature which
shows that the negative effect of land inequality on growth is usually found to be stronger than income
inequality. See Alesina and Rodrik (1994) and Deininger and Squire (1998).
Economies, who typically have high non-labor income and low human capital, do not
produce quality children efficiently. As a result, rich men in less-developed economies
have a low demand for quality children, which translates into a low demand for quality
in women, since quality in women is valued only for its advantage in producing quality
children. Hence, the value of women in themarriage market is determined by the quantity,
rather than the quality of children that women can produce. Assuming that all women
produce a similar expected number of children, all women are close substitutes for each
other in the marriage market in primitive economies, which keeps the price low enough
so that rich men can afford more than one wife. Consequently, rich men in primitive
economies marry multiple wives and have many children with low levels of human capital.
In more advanced economies, human capital plays a larger role in determining the
level of income and inequality. Therefore, the wealthy men are typically men of higher
quality, not just thosewithmore non-labor income. As a result, wealthy men have a higher
demand for child quality versus quantity because their cost of producing child quality is low
relative to the return. The increased demand for quality children increases the demand
for quality in women in the marriage market, since high quality men and women are
complements in the production of quality children. Thus, women are valued according to
both the quality and quantity of children they can produce, and therefore, high quality
women are a scarce resource in the marriage market in advanced economies. As a result,
women of different quality levels are not highly substitutable for each other, and the high
value of quality women increases their price in the marriage market and makes polygyny
less affordable for rich men who want high quality wives. Monogamy emerges in advance
economies because of the increasing value of high quality women in the marriage market,
which stems from the increasing value of their input in the production of child quality.2
In other words, male inequality generates polygyny, but female inequality reduces it.
The model shows that inequality in the value of women is necessary to reduce the degree
of polygynous mating — there needs to be a reason why rich men are willing to pay more
for less quantity. The model also shows how female inequality is generated. The value
of women in the marriage market is shown to be directly linked to the importance of her
children’s human capital. Therefore, when human capital is a bigger factor in determining
Theoretically, the switch towards quality versus quantity in advanced economies, as in Becker, Murphy
and Tamura (1990), could increase the demand for polygyny if a rich man tries to increase quality by
decreasing the number of children per wife, and therefore, may lead to an offsetting increase in the number
of wives. This equilibrium does not occur in our model since the comparative advantage of quality women
in producing quality children drives up the price of quality women to the point of making polygyny less
affordable.
Her child’s future income, women who can create high quality children more efficiently are
increasingly valued in comparison to low quality women. This inequality within women
directly influences the degree of polygynous matching in equilibrium. As a result, male
inequality in less-developed societies translates into inequality in the number of wives per
man, while inequality in developed countries generates inequality in the quality of wives.
Becker (1991) calls inequality in the quality of wives “implicit polygyny,” which our model
shows is the equilibrium outcome when the source of inequality stems mainly from human
capital because of the inequality in the value of women in the marriage market.
The model also offers an explanation of why and how the “power of women” is higher
in advanced societies. The increasing “power of women” derives from the increasing value
of their ability to produce quality children, and therefore, the model is consistent with the
roughly equal division of household resources within modern, monogamous marriages. In
addition, our analysis using data from Cote d’Ivoire confirms all the main implications of
the model. In particular, we control for a man’s total income and show that polygyny
increases with non-labor income but decreases with labor income and education. This
result is consistent with the main prediction of our model: the sources of income, in addition
to the level of income, strongly determine the degree of polygynous behavior in the marriage
market.
It may be tempting to argue that the mystery of monogamy is easily explained by
bans on polygynous behavior in modern societies, or social norms in favor of monogamy.
We do not dismiss these factors as inconsequential, however, they are unlikely to be the
entire explanation for several reasons. First of all, bans on polygyny may seem to be
effective in Western countries, but polygyny is also banned in many less-developed countries
with persistently high rates of polygynous mating (Western Africa, Thailand, Egypt,
etc.). Clearly, bans on polygyny do not guarantee monogamy, precisely because of the
difficulty of enforcement — it is very hard to stop consenting adults from living together
and having children. Secondly, if there are effective laws or norms against polygyny, how
did they arise? If their existence is independent from economic considerations, then norms
against polygyny should not be so strongly correlated with economic development, investments
in child quality, assortative mating between high quality husbands and wives, and
the increasing power of women within the household and in society. Furthermore, our
analysis on Cote d’Ivoire shows that the different sources of income explain variation in
the polygynous behavior of individuals within religion and area of residence, where social
norms about polygyny are likely to be constant.
Therefore, it seems more likely that norms and economic motives work together
and reinforce each other. This line of reasoning follows Becker (1991) and Elster (1989),
who argue that although laws and norms may affect behavior, they rarely evolve and are
maintained if personal incentives are very weak to uphold them. Our model should be
considered an attempt to explain how personal incentives align themselves with norms
at various stages of development. In particular, our model shows how the demand for
polygyny declines naturally in advanced countries, so that social norms can evolve and
reinforce a monogamous outcome. As a result, our model can help explain why norms in
favor of monogamy are strongly correlated with so many economic patterns listed above.
In addition, our model can be used to show within a simple political economy context
why monogamous norms and laws emerge in the first place. Becker (1991) points out that,
in contrast to conventional wisdom, women are not the ones primarily harmed by polygyny,
since polygyny offers additional options for women. The real victims of polygyny are poor
men, who may face very dim marriage prospects if they have to compete with rich men in a
polygynous market. Given that rich men usually exercise more political and social power
than poor men, rich men will only create laws or norms allowing for polygyny when their
benefit from polygyny is high relative to the potential costs of social unrest stemming from
inequality in the marriage market. That is, in advanced countries, the political economy
gains for rich men of giving the “benefit” of monogamy to poorer men outweighs the rather
small cost of limiting themselves to only one wife, which our model predicts is already the
equilibrium tendency. But, in poorer countries where the demand for polygyny by rich
men is high according to our model, the cost of limiting themselves to one woman is very
high, and therefore, the rich and powerful are likely to keep the privilege of polygyny for
themselves and deal with the potential wrath of the lower classes in other ways.
Considering the prevalence of polygyny throughout history and even today in many
less-developed economies, there is surprisingly very little written about this issue.3 Most
models about marriage behavior assume monogamous mating. Becker (1991) presents
the classic model of the marriage market which does allow for multiple partners, and
It is somewhat debatable whether there is no polygyny in modern societies like the United States.
Even if we disregard certain Mormon groups which are explicitly polygynous, many men are “serial
monogamists” in the sense of marrying multiple wives in succession. This could be considered a form of
polygyny, and points to the overall difficulty in categorizing various societies over time as either polygynous
or monogamous. The very definition of marriage is not comparable in all places and over time.
For example, concubines in China had certain privileges which were similar to wives, and the concept of
marriage in Africa today is not the same as in Western societies. However, despite all this variation,
our model seeks to explain the seemingly ubiquitous decline in polygyny in modern societies, using the
working definition of a “wife” as someone a man lives with and raises children with.
Author
